/*
 *   This program is free software: you can redistribute it and/or modify
 *   it under the terms of the GNU General Public License as published by
 *   the Free Software Foundation, either version 3 of the License, or
 *   (at your option) any later version.
 *
 *   This program is distributed in the hope that it will be useful,
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *   GNU General Public License for more details.
 *
 *   You should have received a copy of the GNU General Public License
 *   along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

/*
 *    ProtectedProperties.java
 *    Copyright (C) 2001-2012 University of Waikato, Hamilton, New Zealand
 *
 */

package weka.core;

import java.io.InputStream;
import java.util.Enumeration;
import java.util.Map;
import java.util.Properties;

/**
 * Simple class that extends the Properties class so that the properties are
 * unable to be modified.
 * 
 * @author Richard Kirkby (rkirkby@cs.waikato.ac.nz)
 * @version $Revision$
 */
public class ProtectedProperties extends Properties {

    /** for serialization */
    private static final long serialVersionUID = 3876658672657323985L;

    /** the properties need to be open during construction of the object */
    private boolean closed = false;

    /**
     * Creates a set of protected properties from a set of normal ones.
     * 
     * @param props the properties to be stored and protected.
     */
    public ProtectedProperties(Properties props) {

        Enumeration<?> propEnum = props.propertyNames();
        while (propEnum.hasMoreElements()) {
            String propName = (String) propEnum.nextElement();
            String propValue = props.getProperty(propName);
            super.setProperty(propName, propValue);
        }
        closed = true; // no modifications allowed from now on
    }

    /**
     * Overrides a method to prevent the properties from being modified.
     * 
     * @return never returns without throwing an exception.
     * @throws UnsupportedOperationException always.
     */
    @Override
    public Object setProperty(String key, String value) {

        if (closed) {
            throw new UnsupportedOperationException("ProtectedProperties cannot be modified!");
        } else {
            return super.setProperty(key, value);
        }
    }

    /**
     * Overrides a method to prevent the properties from being modified.
     * 
     * @throws UnsupportedOperationException always.
     */
    @Override
    public void load(InputStream inStream) {

        throw new UnsupportedOperationException("ProtectedProperties cannot be modified!");
    }

    /**
     * Overrides a method to prevent the properties from being modified.
     * 
     * @throws UnsupportedOperationException always.
     */
    @Override
    public void clear() {

        throw new UnsupportedOperationException("ProtectedProperties cannot be modified!");
    }

    /**
     * Overrides a method to prevent the properties from being modified.
     * 
     * @return never returns without throwing an exception.
     * @throws UnsupportedOperationException always.
     */
    @Override
    public Object put(Object key, Object value) {

        if (closed) {
            throw new UnsupportedOperationException("ProtectedProperties cannot be modified!");
        } else {
            return super.put(key, value);
        }
    }

    /**
     * Overrides a method to prevent the properties from being modified.
     * 
     * @throws UnsupportedOperationException always.
     */
    @Override
    public void putAll(Map<? extends Object, ? extends Object> t) {

        throw new UnsupportedOperationException("ProtectedProperties cannot be modified!");
    }

    /**
     * Overrides a method to prevent the properties from being modified.
     * 
     * @return never returns without throwing an exception.
     * @throws UnsupportedOperationException always.
     */
    @Override
    public Object remove(Object key) {

        throw new UnsupportedOperationException("ProtectedProperties cannot be modified!");
    }

}
